Design Of Integrated Polarization Navigation Sensor Based On Imaging Principle

As a kind of astronomical navigation,bionic polarization navigation has the advantages of complete autonomy,less susceptibility to interference,and no time accumulation error,which has attracted widespread attention at home and abroad.At present,the camera-based polarization navigation sensor utilized cameras and linear polarizers to detect sky polarized light.It required at least three imaging modules to solve the sky polarization information,which means complicated structure and lack of real-time processing capability.Inevitably,there was installation error between each imaging modules,which limiting its application scenarios.To solve the problems of complex structure and poor real-time processing capability of the camera-based polarization sensor,this paper designed an integrated polarization navigation sensor based on imaging principle.On the surface of the CMOS image sensor,a double-layer metal nanograting with four polarization units in different directions was integrated to detect polarized light in multiple directions by a single imaging module.It greatly reduced the overall size of the sensor,and the relative angle of each polarization unit was accurate,which means there was no assembly error caused by discrete devices.The sensor,with the STM32F767 series MCU as the main control chip,had real-time processing capabilities.The embedded software was also designed to resolve the polarization information and output through the serial port.To calibrate the system error of the sensor,an Ethernet interface was added to the sensor,which could directly output the polarization information picture to the upper computer.The upper computer calibration software was designed to receive the polarization information picture from the sensor and get the calibration coefficient for the sensor.The optical performance of the integrated polarization navigation sensor was corrected under the ideal polarized light environment indoors.The measurement error of the sensor after calibration was below ±0.1°.To eliminate the effect of random occlusion on the sensor in the outdoor environment,a self-adaptive robust algorithm which could work in different ambient light was added.The measurement error in outdoor static experiments was below ±0.4°.The sensor was mounted on the mobile robot for the dynamic navigation experiment,which indicated that the proposed integrated polarization navigation sensor could provide heading information and was suitable for portable vehicle navigation.